Help support the forum and get %15 Off the Marauder and Accessories direct from Crosman using the coupon code MROD4RUM by CLICKING HERE

[mlee]

Inspired by another airgun mod maker and since you can't readily buy them (that I know of), I decided to make my own to test out. I machined the flange to tighter tolerances than the OEM part so that an o ring would not be necessary and it eliminates the chances of the o ring deforming and causing barrel shifts; thus poor accuracy. I also designed it so that there would be no need to cut one of the baffles, it is a painless drop in fit that replaces the original. I made the port holes around the stripper larger than OEM to air in greater air dispersion. Right away after installing the new air stripper, I noticed big deference in noise, it sounded much quieter and the sound signature was shorter. Over the next few days, I will be doing accuracy testing, comparing the OEM part against my custom made part using the more accurate pellet in my rifle, the 21 grains barracudas at 25 yards. The initial test shots I took after reassembly showed greater improvement in group sizes over the OEM.

[Motorhead]

Without the o-ring on strippers O.D. your going to likely hear vibration from the shroud ringing. Accuracy "May" ? also suffer from harmonics typically dampened by the o-ring now allowing more barrel wiggle during the shot cycle.

Just sharing thoughts here

[mlee]

Without the o-ring on strippers O.D. your going to likely hear vibration from the shroud ringing. Accuracy "May" ? also suffer from harmonics typically dampened by the o-ring now allowing more barrel wiggle during the shot cycle.

Just sharing thoughts here

No, no. I value constructive thoughts as it illuminates a perspective that I may not see right away.

If the OD of the flange was loosely made and inadequate pressure from the end cap that compresses the o ring, I believe you would get ringing but I have not experienced that with the custom part. Regarding accuracy, my initial findings did not show a deviation in accuracy at 15 yards but I will be shooting for groups over the next few days, collecting data and posting my results with photos of the groups; OEM vs custom.

[Motorhead]

at 15 yards, likely WON'T see a difference ( Too close ) need to get out at 40-50+ to see what flight path and POI change happen if any

[Bill G]

Nice part. I made one that made my rifle an extra ~1.5" longer. It is a bit different and works quite well. I to chose not to use an o-ring and went with a tight fit. Mine has long tear shaped holes that narrow in the direction of the muzzle and is made from ABS plastic. I also press fit a cone in the end of it that has a clearance hole of .281". The end of the cone extends about 1/16th" past the narrowest part of the tear shaped passages. At the higher fpe That I'm shooting, it is very effective at reducing report. I haven't found it to adversly affect accuracy and the nois has only gotten more quiet. The snapping turtles in my pond hate it, atleast the ones that witnessed the last victim

[louigi600]

Nice work.
How do you get the holes on the sides evenly spaced ?
Do you have a lathe/mill combo with indexing wheel ? or what other trick do you use to get them all evenly spaced ?

[SHOOTINIT]

i'll stick with the oring.

[louigi600]

Ok this is what I mean by making the hole which the pellet goes trough longer (to increase air stripping)

and a video showing it a bit better:
http://youtu.be/1gEH7IgnmVI

[bumper]

I decided to stay with the O-ring as well. As received, there were burrs on the OD of the muzzle on my .22 M-rod. These scraped the Delrin and the swarf was contacting the pellets - - not good for accuracy.

Made a new stripper out of aluminum, original on the left:





I attempted to address a couple of issues; the extended "barrel" gives the gas a bit more time to pass more volume into the shroud before the pellet exits into the baffle area. The somewhat smaller bore diameter of the stripper, as compared to stock (I used .250 instead of the stock .280 +/-) also helps . . . (EDIT, I goofed, the stock stripper has an ID of .250", I used .230"). I used two rows of port holes for the same reason. (The stock stripper shown was previously modified with oversize holes.) I designed my new stripper so it fits with stock baffles, though I may make new baffles later on.

To help prevent "POI drift", that some have ascribed to storing the gun so that pressure is applied to the barrel shroud, thus giving the O-ring a "set", I increased the OD of the O-ring groove by .004". Stock, the groove OD measures .590" and the O-ring is about .100" thick. Uncompressed, O-ring OD is then about .790" and the shroud ID is .780". I allowed for the additional O-ring compressing by making my groove .120" wide. Greased the O-ring with silicone grease and it slid into place with no problems - - noticeably tighter fit.

The gas stripper is an interference fit onto the barrel, tapped into place with a small hammer and hardwood block. To remove, use a grooved hardwood block to slip over barrel behind stripper, then tap to remove.

No POI shift observed. Sounds quieter though it was already pretty quiet to begin with. Previously installed an aluminum de-pinger with O-ring. Center of de-pinger is drilled and tapped 1/4 - 20, so a length of all-thread can be used to remove the de-pinger if need be.

This is my first post. As a new M-rod owner, I've been reading this forum and it's been a big help. Thanks!

all the best,

bumper

[RayK]

I think these are all cool. We need some scientific way to evaluate each one. I tried to start this a while back by buying a sound pressure meter, but found it was not of the appropriate type to detect subdtle differences in shot loudnesses.

I've seen some on here post images of sound waves - perhaps captured by their computers. Maybe some of them can chime in with recommendations.

I think the o-ring is still a good idea, but the shroud spacer should be very close tolerance to the ID of the shroud to keep the POI from moving. This inner shroud spacer combined with something to shim the outer gap between the shroud and the barrel band seems to eliminate the POI shift and increases group accuracy.

Ray